Camshaft adjusters are used in internal combustion engines to vary the timings of the combustion chamber valves in order to make it possible to vary the phase relationship between a crankshaft and a camshaft in a defined angle range, between a maximum early position and a maximum late position. Adapting the timings to the instantaneous load and speed lowers the consumption and the emissions. For this purpose, camshaft adjusters are integrated into a drivetrain, via which a torque is transmitted from the crankshaft to the camshaft. This drivetrain may be designed for example as a belt drive, a chain drive or a gear wheel drive.
In a hydraulic camshaft adjuster, the output element and the drive element form one or multiple pairs of pressure chambers acting in opposition, to which hydraulic medium may be applied. The drive element and the output element are arranged coaxially. By filling and emptying individual pressure chambers, a relative movement between the drive element and the output element is generated. The spring acting rotatively between the drive element and the output element pushes the drive element into an advantageous direction relative to the output element. This advantageous direction may be in the same direction or in the opposite direction with respect to the direction of rotation.
One type of hydraulic camshaft adjuster is the vane cell adjuster. The vane cell adjuster includes a stator, a rotor and a drive wheel with external teeth. As the output element, the rotor is usually designed to be rotatably fixedly connectable to the camshaft. The drive element includes the stator and the drive wheel. The stator and the drive wheel are rotatably fixedly connected to each other or, as an alternative, are formed in one piece with each other. The rotor is arranged coaxially to the stator and arranged inside the stator. The rotor and the stator form, with their radially extending vanes, oil chambers which act in opposition and to which oil pressure may be applied, and enable a relative rotation between the stator and the rotor. The vanes are either formed in one piece with the rotor and the stator or are arranged as “inserted vanes” in grooves provided for this purpose in the rotor and the stator. In addition, the vane cell adjusters have various sealing covers. The stator and the sealing covers are secured to each other via multiple screw connections.
Another type of hydraulic camshaft adjuster is the axial piston adjuster. In this case, a displacement element is displaced axially by way of oil pressure, and generates a relative rotation between a drive element and an output element via helical toothings.
Another type of camshaft adjuster is the electromechanical camshaft adjuster, which includes a triple shaft gear (for example a planetary gear). In this case, one of the shafts forms the drive element and a second shaft forms the output element. Via the third shaft, rotational energy may be supplied to or discharged from the system with the aid of an actuator, for example an electric motor or a brake. A spring may additionally be provided, which assists or returns the relative rotation between the drive element and the output element.
DE 10 2005 062 522 A1 describes a method for the force-fitting connection of the end faces of two machine components in order to transmit high torques or transverse forces, as well as an assembly formed of these machine components which is produced according to this method. Force-fitting connections between two surfaces of machine components are used in many areas of mechanical engineering to transmit transverse forces or torques. The transmittable force is effectuated substantially by the surface pressure and the resulting friction between the surfaces that are connected to each other. Such connections are particularly important in drive technology, for example for driving ancillary units. The transmittable power is often limited by the force that may be transmitted via the contact between the two surfaces abutting against each other.
DE 10 2009 050 779 A1 describes a swivel motor camshaft adjuster including a rotor and a camshaft. A friction disk is clamped axially between this rotor and the camshaft with the aid of a central screw. This friction disk thus transmits a drive torque frictionally engaged. For swiveling the rotor in two opposite directions of rotation, at least two oil channels extend through the camshaft and a hub of the rotor. At least one oil channel is hydraulically sealed on the inside in the radial direction by an inner ring part of the friction disk and on the outside in the radial direction by an outer ring part of the friction disk.